In the automotive wheel production industry, the spraying process is an important factor affecting the appearance and safety of the wheel. According to the requirements of the automobile manufacturer, paint is not allowed at the matching part of a wheel bolt hole and a mounting bolt. The wheel manufacturer usually uses a bolt hole guard to achieve the aforesaid function. However, the gap between the guard and the bolt hole, leads the paint to be sprayed on the wheel bolt hole, on which paint is not allowed. How to effectively protect the part of the wheel that paint is not allowed on is a problem that the wheel manufacturer must to face.